GB1559996A - Exhaust device for internal combustion engine - Google Patents

Description

(54) EXHAUST DEVICE FOR INTERNAL COMBUSTION ENGINES (71) 1, GUY HENRI BANCEL, a Citizen of France of 83 rue Petit, 75019 Paris, France, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it-is to be performed, to be particularly described in and by the following statement:- This invention has farits object an exhaust device for internal combustion engines.

It has already been suggested, in order to improve the performance of certain internal combustion engines, to shape their exhaust pipes with a diverging section then a converging section as seen ín the; direction of the gas - flow, such a device being sometimes referred to as an "extractor". Apart from the fact that such devices are only fully operational over a small range of the operating conditions of the engine, i.e in a small range of rotational speeds, their use does not satisfy the imposed requirements of noise level limitations for the exhaust of the engine which is equipped with them.

Whereas there exists a large number of silencer devices for internal combustion engines, of the type comprising deflectors or absorbing materials, the construction of such silencers results in perturbations in the flow of exhaust gases, which generally results in a reduction in performance of the engines with which they are associated.

It is an object of this invention to provide an exhaust device for use with internal combustion engines, which device eliminates the disadvantages of the above mentioned silencers and which leads to an improvement in the performance of the engine which is equipped with it, at least as significant as that obtained by means of devices of the "extractor" type, without presenting the disadvantages inherent in these devices.

It is also another object of this invention to provide such a device which, in contrast to known devices of the "extractor" type, is operational over a very wide operating range of the engine which is equipped with it.

According to this invention, an exhaust device for internal combustion engines comprises a pipe which includes a first sectiorl- having a progressively increasing cross-sçction and then a second section with a progressively decreasing cross-section as seen in the direction of flow ofthe exhaust gases said section with progressivelY decreasir3g-cyqss- section comprising an external substantially cylindrical envelope and a - stre-am-lined member with art ogival or - conical surface disposed within said envelope substantia2ly coaxially therewith such that the exhaust gases flow, without any-perturbation of the fluid stream, through said cylindrical envelope and pass out of said device though a down stream end of the envelope.

The streamlined member may be mounted in the external^envelope for movement along the axis thereof and in a preferred embodiment, such movement is varied with the engine operating conditions.

The invention will be better understood from the following description given as an example with reference to the accompanying drawing wherein: Figure 1 is a diagrammatic longitudinal sectional view of a device according to this invention; Figure 2 is an end view of the device as seen in the direction of arrow A of Figure 1; Figure 3 is a view similar to that of Figure 1, but for an alternative embodiment.

An internal combustion engine exhaust device 10, according to this invention is shown in Figures 1 and 2 as comprising a diverging section 11 connected to an engine M and which extends, in the direction of flow of the exhaust gases shown by an arrowf, into an external envelope 12. Within the latter, which is preferably of cylindrical shape, is mounted by means of supports 13 and 14, a streamlined member 15 which in conjuction with the envelope 12 defines a flow path 16 with a cross-sectional area progressively decreasing in the direction of flow of the exhaust gases.

In an embodiment, the streamlined member 15 has an ogival or conical surface with a vertex 19, and with its axis 20 preferably coaxial with the axis 21 of the envelope 12.

The streamlined member 15 is preferably movably mounted inside envelope 12, the direction of possible movement being to and fro along the line of arrowf. This movement is effected by means, not shown, adapted to be varied with the operating conditions of the engine through a connection 17 from a member 18, which can for example, be the throttle control of a motor-cycle engine or the accelerator pedal of a car engine, when the engine is that of a motor vehicle.

The operation of a device according to this invention is similar to that of a device of the "extractor" type with regard to the flow of the exhaust gases. In the device of the invention, however, the vertex 19 of the streamlined member 15 acts upon the sound wave system to cause a vibration node to appear at said vertex with a consequent decrease in noise relatively to that generated by the usual type of exhaust.

Complementarily, the longitudinally displaceable mounting of the streamlined member 15 and the control of the movement subject to the operating conditions of the engine through throttle connection 17 enables an automatic adjustment of the flow characteristics of the exhaust gases in relation to the rotational speed of the engine, the efficiency of which is thus improved continuously.

In an alternative embodiment shown in Figure 3, all or part of the length of the envelope 12, is provided with punched openings, and is surrounded by a sleeve member 22 of an acoustically insulating matterial, such as glass fibre or rock wool, enclosed in an external tubing 23.

In such a device, the operation of which is similar to that of the embodiment described hereabove, the absorption of the high frequency sound by the sleeve 22 contributes to the achievement of a particularly satis factory sound level.

WHAT I CLAIM IS: 1. An exhaust device for an internal combustion engine comprising a pipe which includes a first section having a progressively increasing cross-section and then a second section with a progressively decreasing crosssection as seen in the direction of flow of the exhaust gases, said section with progressively decreasing cross-section comprising an external substantially cylindrical envelope and a streamlined member with an ogival or conical surface disposed within said envelope substantially coaxially therewith such that the exhaust gases flow, without any perturbation of the fluid stream, through said cylindrical envelope and pass out of said device through a downstream end of the envelope.

2. Device according to claim 1, wherein the streamlined member is mounted for move- ment along the axis of the external envelope, said movement being varied with the rotational speed of the engine.

3. Device according to claims 1 or 2, wherein the external envelope is perforated and is covered on the whole or in part of its length with a sleeve of acoustically insulating material such as rock wool, or glass fibre.

4. A device according to any one of claims 1 to 3, wherein said streamlined member has a vertex and is so mounted that said vertex acts upon the sound wave of exhaust gases to produce a vibration node at said vertex.

5. An exhaust device for an internal combustion engine substantially as hereinbefore described with reference to and as shown by the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. The streamlined member 15 is preferably movably mounted inside envelope 12, the direction of possible movement being to and fro along the line of arrowf. This movement is effected by means, not shown, adapted to be varied with the operating conditions of the engine through a connection 17 from a member 18, which can for example, be the throttle control of a motor-cycle engine or the accelerator pedal of a car engine, when the engine is that of a motor vehicle. The operation of a device according to this invention is similar to that of a device of the "extractor" type with regard to the flow of the exhaust gases. In the device of the invention, however, the vertex 19 of the streamlined member 15 acts upon the sound wave system to cause a vibration node to appear at said vertex with a consequent decrease in noise relatively to that generated by the usual type of exhaust. Complementarily, the longitudinally displaceable mounting of the streamlined member 15 and the control of the movement subject to the operating conditions of the engine through throttle connection 17 enables an automatic adjustment of the flow characteristics of the exhaust gases in relation to the rotational speed of the engine, the efficiency of which is thus improved continuously. In an alternative embodiment shown in Figure 3, all or part of the length of the envelope 12, is provided with punched openings, and is surrounded by a sleeve member 22 of an acoustically insulating matterial, such as glass fibre or rock wool, enclosed in an external tubing 23. In such a device, the operation of which is similar to that of the embodiment described hereabove, the absorption of the high frequency sound by the sleeve 22 contributes to the achievement of a particularly satis factory sound level. WHAT I CLAIM IS:

1. An exhaust device for an internal combustion engine comprising a pipe which includes a first section having a progressively increasing cross-section and then a second section with a progressively decreasing crosssection as seen in the direction of flow of the exhaust gases, said section with progressively decreasing cross-section comprising an external substantially cylindrical envelope and a streamlined member with an ogival or conical surface disposed within said envelope substantially coaxially therewith such that the exhaust gases flow, without any perturbation of the fluid stream, through said cylindrical envelope and pass out of said device through a downstream end of the envelope.

2. Device according to claim 1, wherein the streamlined member is mounted for move- ment along the axis of the external envelope, said movement being varied with the rotational speed of the engine.

3. Device according to claims 1 or 2, wherein the external envelope is perforated and is covered on the whole or in part of its length with a sleeve of acoustically insulating material such as rock wool, or glass fibre.

4. A device according to any one of claims 1 to 3, wherein said streamlined member has a vertex and is so mounted that said vertex acts upon the sound wave of exhaust gases to produce a vibration node at said vertex.

5. An exhaust device for an internal combustion engine substantially as hereinbefore described with reference to and as shown by the accompanying drawings.